This disclosure relates to counter circuitry and methods.
Some data processing apparatuses have a central ‘always-on’ source of time, known as the system counter that monotonically increases. This continuous count source is distributed to all processing elements in the system in such a way that the observation of this source is consistent and does not, through communication between processors, lead to time appearing to move backwards.
Some techniques for distributing this signal involve using distributed counters. Each distributed counter must be accurately synchronized to the current, continuously incrementing, always-on system counter offset when it is powered-on and before any processor observes it.
A consequence of distributing the counters is that they may be power-cycled quite frequently and therefore the synchronization potentially needs also to occur frequently.